We're dividing 71537421 by 821 
The aim is to understand the frequency of 821 in 71537421.

On to step 1:
When dividing 7 by 821, we get 0 with a remainder of 7.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 7 leaves us with 7.
Append the next digit (1) from the dividend to 7 and continue with: 71 / 821

Going ahead to step 2:
When dividing 71 by 821, we get 0 with a remainder of 71.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 71 to get 71.
Append the next digit (5) from the dividend to 71 and continue with: 715 / 821

On to step 3:
715 divided by 821 is 0 with a remainder of 715.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 715 leaves us with 715.
Fetch the next digit (3) from the dividend, attach it to 715 and continue: 7153 / 821

Moving on to step 4:
821 can be fit into 7153 8 times, resulting in a remainder of 585.
Use 8 as the next digit of our solution. 
Result so far: 8.0
Subtracting 6568 from 7153 leaves us with 585.
Bring next digit (7) of the dividend behind the 585 and repeat the process: 5857 / 821

Advancing to step 5:
If we divide 5857 by 821, we get 7 and a remainder of 110.
Put 7 as the next digit of the answer. 
Result so far: 87.0
Deduct 5747 from 5857 and we're left with 110.
Append the next digit (4) from the dividend to 110 and continue with: 1104 / 821

Let's proceed to step 6:
When dividing 1104 by 821, we get 1 with a remainder of 283.
Put 1 as the next digit of the answer. 
Result so far: 871.0
If we take 821 away from 1104, we end up with 283.
Include the next digit (2) from the dividend after 283, then repeat: 2832 / 821

Step 7:
When dividing 2832 by 821, we get 3 with a remainder of 369.
The number 3 becomes the next digit in our result. 
Result so far: 8713.0
The remainder is 369 after subtracting 2463 from 2832.
Append the next digit (1) from the dividend to 369 and continue with: 3691 / 821

Going ahead to step 8:
The number 821 fits into 3691 4 times, leaving a remainder of 407.
The next digit of our result is 4. 
Result so far: 87134.0
Subtract 3284 from 3691 to get 407.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4070, and continue the process.

Let's proceed to step 9:
4070 divided by 821 is 4 with a remainder of 786.
Put 4 as the next digit of the answer. 
Result so far: 87134.4
If we subtract 3284 from 4070, we get 786.
Since there are no more digits in the dividend, we add a zero to the remainder making it 7860, and continue the process.

Step 10:
821 can be fit into 7860 9 times, resulting in a remainder of 471.
Record the quotient 9 as the next digit in the result. 
Result so far: 87134.49
Subtracting 7389 from 7860 leaves us with 471.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4710, and continue the process.

On to step 11:
821 goes into 4710 5 times with a remainder of 605.
The number 5 becomes the next digit in our result. 
Result so far: 87134.495
Subtract 4105 from 4710 to get 605.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6050, and continue the process.

Let's proceed to step 12:
821 goes into 6050 7 times with a remainder of 303.
The next digit of our result is 7. 
Result so far: 87134.4957
The remainder is 303 after subtracting 5747 from 6050.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3030, and continue the process.

Step 13:
3030 divided by 821 is 3 with a remainder of 567.
Write down 3 as next digit of the result. 
Result so far: 87134.49573
The remainder is 567 after subtracting 2463 from 3030.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5670, and continue the process.

Step 14:
When dividing 5670 by 821, we get 6 with a remainder of 744.
Record the quotient 6 as the next digit in the result. 
Result so far: 87134.495736
If we subtract 4926 from 5670, we get 744.
Since there are no more digits in the dividend, we add a zero to the remainder making it 7440, and continue the process.

Going ahead to step 15:
821 can be fit into 7440 9 times, resulting in a remainder of 51.
Record the quotient 9 as the next digit in the result. 
Result so far: 87134.4957369
Subtracting 7389 from 7440 leaves us with 51.
Since there are no more digits in the dividend, we add a zero to the remainder making it 510, and continue the process.

Step 16:
821 goes into 510 0 times with a remainder of 510.
Record the quotient 0 as the next digit in the result. 
Result so far: 87134.4957369
Subtract 0 from 510 to get 510.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5100, and continue the process.

Our division results in 87134.4957369 with a remaining 5.1e-07.